The Knife with Mt Simms and Planningtorock - Tomorrow, in a Year

For fans of The Knife, the news that the Swedish electro duo had been commissioned by Danish performance art group Hotel Pro Forma to produce an opera based on Charles Darwin's Origin of the Species was heartening indeed. After three highly iconoclastic, innovative albums, culminating with 2006's Silent Shout, it seemed siblings Karin Andersson and Olof Dreijer felt they had mined their musical partnership of its worth and rumours of an indefinite sabbatical circulated. Last year, Andersson's solo work, released under the moniker Fever Ray, was deservedly garlanded with praise by critics, although with its nocturnal rhythms and Grimm's fairytale imagery, it felt almost like an addendum to Silent Shout.

So it's fantastic to have the duo back together again. However, those welcoming The Knife back with open arms should be aware of what they're getting. Sprawling over two CDs, Tomorrow, in a Year is a collaboration between The Knife, two Berlin-based electronic artists, Planningtorock and Mt Simms, as well as Icelandic percussionist Hjorleifur Jonsson. It's also a work intend for the stage, and without that visual element it can be difficult to guess the context in which certain tracks are meant to be understood. For example, what to make of 'Shoal Swarm Orchestra', the extended sound collage which closes CD one and evolves from placid bird song to industrial scraping, heavy rainfall and the braying of what sounds like a half-horse-half-motorbike? Without seeing the opera (which has so far been performed in Copenhagen and Athens with more dates TBA) it's somewhat difficult to gauge the success of these more obtuse moments, except to say that they make for a simultaneously impressive, enthralling and perplexing listen, which is all you can ask from music this determinedly avant garde.

So what can we make sense of here? At the start of January, a heavily percussive, bracingly dramatic track named 'Colouring of Pigeons' was made available to download on theknife.net as a taster for Tomorrow, in a Year. Now that the full work has been made available for download on the same site, ahead of its physical release on March 1, we can see that 'Colouring of Pigeons' is not in fact indicative of Tomorrow, in a Year as a whole. Rather, it forms the point where the disparate strands which run through the opera - the explosive vocals of mezzo-soprano Kristina Wahlin, the hyper-dense percussion, the abrasive industrial noise - coalesce and react to create the album's most complete, and utterly captivating, statement. And the rest? Well, anyone looking for a killer, 80s-informed dancefloor hit such as 'Heartbeats' from 2003's Deep Cuts is in the wrong place. The closest we get is the sprightly minimalist electro of 'Seeds' towards the end of CD two, which, with its interlocking chimes and analogue synths, sounds like David Bowie's Berlin-era instrumental 'Weeping Wall' if it had been produced by Steve Reich.

Generally speaking, CD one is more heavy going; its dense, percussive tracks are interspersed with more ambient works, such as 'Ebb Tide Explorer', which recall Krautrockers Faust or proto-industrialists Einstürzende Neubauten. After the static and white noise of opener 'Intro', Wahlin's impassioned vocal appears in 'Epochs' and remains a strong presence throughout. 'Geology' is an early highlight, wherein Wahlin sounds like she's engaged in a vocal duel with a horde of angry Clangers. But the opera's most startling moment is without doubt 'Variation of Birds'. Beginning with an ear-splitting siren wail, it batters you round the brain before varying its tone into a series of degraded, staccato Morse code bleeps over which Swedish singer Jonathan Johansson wails like the ghost of Associates' singer Billy Mackenzie, joined by a Greek chorus of lamenting wraiths. It's genuinely hard work, but you'll feel compelled to listen to it again and again just to try and unpick what on Earth this sound is.

Kicking off the less abrasive second disc, 'Annie's Box', about Darwin's letters to his daughter, is a kinder listen; it's mournful cello and weeping fiddle bringing to mind Godspeed You Black Emperor! at their most sombre and spiritual. Meanwhile, closing track 'The Height of Summer' takes us back to the glorious electro-funk of Silent Shout, it's whiplash rhythm and cute, twinkling melodies recalling that album's standout track, 'We Share Our Mother's Health', and providing an unexpectedly uplifting ending to proceedings.

Overall, this is by no means an easily digestible work; even four or five listens will not be enough to get your head round the whole of Tomorrow, in a Year. And, honestly, it's unclear exactly how the theories Darwin expounded in Origin of the Species influenced this music, although evolution does seem a possible theme. But what's easy to grasp is that Tomorrow, in a Year represents another great leap forward for The Knife. So, for now, let's be glad Karin and Olof considered this project worthy of their reformation and hope that they feel suitably energised from its creation to bring us more of their uniquely confounding, unsettling and brilliant music in the not-too-distant future.

Richard Morris